The present invention relates to a rotary parlour for milking of animals, wherein the rotary parlour comprises an platform having a surface to support animals to be milked, a circular rail member connected to a lower surface of the platform and a plurality of rolling members having a wear surface adapted to be in contact with a wear surface of the rail member such that the platform is rotatably arranged on the rolling members.
A conventional rotary parlour comprises a circular rail member provided with a substantially plane wear surface to be in contact with corresponding plane wear surfaces of rolling members arranged on the underside of the platform. During operation of the rotary parlour, parts of the platform will be deflected by the weight of the cows. The deflection of the platform occurs especially when the cows walk on and leave the platform. Such deflections of the platform may result in locally turning motions of the rail member such that the platform achieves an unstable motion on the rolling members. The turning motions of the rail member cause angular adjustments of the plane wear surface of the rail member in relation to the plane wear surfaces of the rolling members. The contact surface between the wear surfaces is thereby reduced and high local contact pressures are created. The high local contact pressures result in an uneven wearing of the wear surfaces and risk for formation of stress cracks.
Further, the angular adjustments of the rail member result in asymmetrical loads on the roller members. Thereby, the life length of bearings of the roller members can be reduced. Furthermore, the asymmetrical loads also act on weld joints located in the vicinity of the wear surfaces. Weld cracking can occur in such weld joints. The wear surface of a conventional rail member wearing out when about 5 to 10 million cows has been milked on the rotary parlour.